Magnetic resonance imaging apparatus

ABSTRACT

A magnetic resonance imaging apparatus includes a magnet having a two poles and a wall connecting the poles; the poles delimiting a patient-imaging space; and a table which is slidably connected to one of the two poles between the two poles and which table extends substantially parallel to the two poles; a drive for displacing the table relative to the magnet; a lock for locking the table in a selected position relative to the magnet; a drive for rotating the magnet about the axis; the table connected to the magnet such that the table rotates with the magnet when the magnet rotates about the axis; the magnet and the table being rotatable from a position in which the poles and the table are horizontal to a position in which the table and the poles are vertical.

BACKGROUND OF THE APPLICATION

[0001] 1. Field of the Invention

[0002] The invention relates to a magnetic resonance imaging apparatus,and particularly to a multipurpose dedicated imaging apparatus havingimproved features for imaging the region of the vertebral column..

[0003] 2. Description of the Related Art

[0004] Imaging the vertebral column may require the possibility ofbringing the patient in an upright position in order to have thevertebral column loaded by the weight of the patient. In the normallaying down position of the patient on a bed or table having anhorizontal orientation, the vertebral column will be in an unloaded andideal condition. Thus, most pathologies may not arise clearly and theexamination will lead to unclear results or to negative results despitethe fact that the patient is showing typical symptoms of a disease ofthe vertebral column.

[0005] Actually known magnetic resonance imaging apparati use so calledtotal body scanners which magnetic structure houses the entire body or aconsiderable part of it inside the patient examining space defined bythe magnetic structure.

[0006] U.S. Pat. No. 6,414,490 and U.S. Pat. No. 6,504,371 disclosemagnetic resonance imaging apparatus of the above mentioned kind. Themagnetic structure is designed to generate a horizontal magnetic field.The patient is brought inside the examining space by means of a patientpositioning device which is a bed or table mounted on a carriage, whichbed or table can be further tilted around horizontal axis for givingdifferent orientations to the bed or table with respect to the verticaldirection. Furthermore, in order to focus the region of the patient tobe imaged, the bed or table or carriage may be associated with anelevator which displaces the patient up and down relative to theexamining space between the poles of the magnetic structure.

[0007] The actual devices are very big, heavy, and expensive. Big andheavy magnetic structures have problems of installation, since the roomwhere the imaging apparatus has to be installed must necessarily have afloor which can support the weight of the imaging apparatus.Furthermore, the room must be sufficiently big to permit installation.

[0008] The patient positioning device is also relatively expensive dueto the tiltable or swingable bed or table and due to the necessity of anelevator for displacing the patient relative to the imaging space in themagnetic structure.

[0009] On the other hand, even if the anatomic region of the vertebralcolumn is a very large one, usually examination through imaging iscarried out for only a certain specific part of the vertebral column.

OBJECTS AND SUMMARY

[0010] An object of the present invention is to provide for a magneticresonance imaging apparatus which has a smaller magnetic structure thanthe conventional so called total body apparatus and which allowsnevertheless imaging of the vertebral column under various conditions.

[0011] A further aim is to provide for such a magnetic imaging apparatuswhich has simpler and less expensive means for positioning the patientin the examination space of the magnetic structure.

[0012] A further object of the present invention is to provide for amagnetic resonance imaging apparatus which can be used also forexaminations of other anatomic regions of the body of the patient, byallowing in a simple way to displace the patient relative to theexamination space in the magnetic structure in order to bring thedesired anatomic region or a certain limited region thereof in theexamination space.

[0013] One embodiment of the present invention includes a magneticresonance imaging apparatus comprising a magnet having a two oppositeand spaced apart poles and a column or wall transverse to the poles andconnecting the poles; the poles defining two opposite walls delimiting apatient-imaging space, the two opposite walls extending alongsubstantially parallel planes which are substantially perpendicular to avertical plane; and a patient positioning table which is slidablyconnected to one of the two poles in a position between the two polesand which table extends substantially parallel to the two oppositepoles; the table being slidable with respect to the magnet in adirection parallel to a longitudinal axis of the table; a drive fordisplacing the table relative to the magnet; a lock for locking thetable in a selected position relative to the magnet; the magnet beingsupported rotatably along a central horizontal axis of the transversewall or column; a drive provided for rotating the magnet about the axis;the table being connected to the magnet such that the table rotates withthe magnet when the magnet rotates about the axis; the magnet and thetable being rotatable from a position in which the poles and the tableare substantially horizontal to a position in which the table and thepoles are substantially vertical, and vice versa; and the rotation ofthe table and the magnet are locked together by the lock.

[0014] Another embodiment of the present invention includes a method formagnetic resonance imaging with a magnetic structure having two oppositepoles spaced apart one from the other and oriented substantiallyperpendicular to a vertical plane and defining a patient imaging space;and a table for a patient secured to one of the two poles in a slidableway in a longitudinal direction of the table relative to the magneticstructure and between the two poles of the magnetic structure, the tablebeing oriented parallel to the poles, the table having a footrest at oneend thereof, the magnetic structure and the table being rotatabletogether around an axis which is transverse to a longitudinal axis ofthe table and parallel to the table. The method comprises:

[0015] rotating the magnetic structure with the table to a patientpositioning position in which the table is substantially horizontal;

[0016] sliding the table to an end position, in which a part of thetable is outside the magnetic structure;

[0017] arranging the patient on the table in a lying down position;

[0018] sliding the table along its longitudinal axis relative to themagnetic structure until the magnetic structure is correctly centeredwith a part of the patient's body to be examined;

[0019] locking the table relative to the magnetic structure togetherwith the table in a position in which the table is not horizontal orvertical;

[0020] carrying out an imaging procedure;

[0021] rotating the magnetic structure together with the table to aposition in which the table is substantially horizontal; and

[0022] sliding the table to one of two positions in which a part of thetable is outside the magnetic structure and letting the patient stepdown from the table.

[0023] Another embodiment of the present invention includes a method forcarrying out magnetic resonance imaging with providing a magneticstructure having two opposite poles spaced apart one from the other andoriented substantially perpendicular to a vertical plane and defining apatient imaging space; and a table having a footrest at one end andslides for engaging guides for a longitudinal displacement of the table;and a table supporting structure which has wheels and which iscompletely independent from the magnetic structure, one of the poles ofthe magnetic structure and the table supporting frame have identicalguides with which the slides of the table are adapted to engage. Themethod comprises:

[0024] rotating the magnetic structure such that the guides for thetable are horizontal and aligning the table supporting frame with theguides of the table supporting frame aligned with the guides on the poleof the magnetic structure; lying the patient down on the table;

[0025] sliding the table along a longitudinal direction thereof awayfrom the table supporting frame and against the pole having the guidesand engaging at the same time a free end of the slides of the table withthe guides on the pole;

[0026] sliding the table with the patient on the table until the tableis completely disengaged from the table supporting frame and engagedwith the pole of the magnetic structure;

[0027] sliding further the table along its longitudinal axis relative tothe magnetic structure until the magnetic structure is correctlycentered with a part of the patient's body to be examined;

[0028] supporting the magnetic structure and the table in such a way asto be rotatable together around an axis which is transverse to thelongitudinal axis of the table and substantially parallel to the table;

[0029] locking the table relative to further sliding and rotating themagnetic structure together with the table with the patient on it in aposition in which the table is not horizontal;

[0030] carrying out the imaging procedure;

[0031] rotating the magnetic structure together with the table back to aposition in which the table is substantially horizontal;

[0032] sliding the table away from the pole of the magnetic structureonto the table supporting frame.

[0033] Another embodiment of the present invention includes a method forcarrying out magnetic resonance imaging with a magnetic structure havingtwo opposite poles spaced apart one from the other and orientedsubstantially perpendicular to a vertical plane and defining a patientimaging space; and a table for a patient to one of the two poles in aslidable way in a longitudinal direction of the table relative to themagnetic structure and between the two poles of the magnetic structure,the table being oriented substantially parallel to the poles; themagnetic structure and the table being rotatable together around an axiswhich is transverse to the longitudinal axis of the table and parallelto the table. The method comprises:

[0034] rotating the magnetic structure together with the table in aposition in which the table is not horizontal;

[0035] providing a seat plate secured at an angle to the table;

[0036] sitting the patient down on the seat plate;

[0037] carrying out the imaging procedure; and

[0038] letting the patient step out of the magnetic structure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The magnetic resonance imaging apparatus and the advantagesthereof will appear more clearly from the following description madewith reference to an embodiment which is illustrated in the annexeddrawings which drawings illustrate:

[0040]FIG. 1 is a schematic frontal view of an embodiment of a magneticresonance imaging apparatus according to the invention.

[0041]FIG. 2 is a schematic lateral view partly sectioned of theapparatus according to FIG. 1.

[0042] FIGS. 3 to 6 are simplified frontal views of an embodiment of theapparatus according to the invention in its position with the tableoriented along the horizontal plane and in different relative positionsof the table with respect to the magnetic structure.

[0043]FIGS. 7 and 8 are perspective views of an embodiment of theapparatus according to the present invention with the magnetic structureand the table in the position in which the table is horizontal and inthe position in which the table is vertical.

[0044]FIG. 9 illustrates a lateral view of an embodiment of theapparatus according to the present invention in which a seat isassociated to the table.

[0045]FIG. 10 illustrates a frontal view of an embodiment of themagnetic resonance imaging apparatus according to the present inventionin combination with a separate supporting frame for the table.

[0046]FIG. 11 shows a partial section of a enlarged particular of oneslide and guide of the table according to one embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] Referring now to the Figures, particularly FIGS. 1 and 2, amagnetic resonance imaging apparatus according to an embodiment of theinvention is schematically illustrated.

[0048] The magnetic resonance imaging apparatus comprises a supportingelement 1 in the form of a vertical wall. A magnetic structure 2 issecured to the supporting element 1 in a overhanging way. The magneticstructure 2 comprises two opposite poles 102, 202 which are orientedperpendicularly with respect to the supporting wall 1, and which areconnected together in a spaced apart relationship by means of a columnor wall 302 which extends parallel to the supporting wall 1 and which issecured to the wall by means of a shaft 3 perpendicular to thesupporting wall 1 and to the transverse connecting wall 302 of themagnetic structure 2. The axis of the shaft 3 which is rotatable in ahousing in the supporting wall and is also parallel to the poles 102,202 and perpendicular to the magnetic field generated between them. Theaxis of the shaft 3 is coincident with the center of symmetry of thewall 302 of the magnetic structure, although this is not a necessaryfeature in order to ensure the functions of the present magneticresonance imaging apparatus.

[0049] A coaxial frontally toothed crown 101 on the supporting wall 1cooperates with a driving pinion 4 which is driven by a motor 5 by meansof a transmission 6. Thus, the motor 5 can cause the rotation of themagnetic structure 2 around the axis of the shaft 3 relative to thesupporting wall 1. Although the frontally toothed coaxial crown 101 isillustrated mounted on the supporting wall 1, the same result could bereached by providing the toothed crown on the wall 302 of the magneticstructure and the motor 5, the transmission 6 and the pinion 4 on thesupporting wall. This solution would avoid elements on the wall 302which could cause disturbance to the circulation of the magnetic fluxwithin said wall 302.

[0050] A table 7 is slidably mounted in a direction parallel to itslongitudinal axis on the lower pole 102 of the magnetic structure. Asused herein, the term “table” may be a bed, bed plate, table plate, orother flat surface on which a patient may lie for purposes ofexamination. The table or bed plate 7 is oriented with its longitudinalaxis perpendicular to the axis of the shaft 3 and parallel to the wall302 of the magnetic structure 2.

[0051] The table 7 is supported slidably in its longitudinal directionby means of a combination of guides and slides, motorized means beingalso provided for deriving the displacement of the said table 7 relativeto the magnetic structure 2.

[0052] In the present embodiment, two longitudinal slides 107 areprovided underneath the table 7 and are secured thereto. The slides 107extend along opposite longitudinal sides of the table 7 are slidablyengaged in guides 8, 8′ provided at the transverse ends of the lowerpole 102 of the magnetic structure.

[0053] A combination of a longitudinal rack secured to the table 7 and apinion driven by a motor ensures a motorised displacement of the tablealong it longitudinal axis and in both directions.

[0054] As illustrated, the racks may be formed also by the one or bothslides 107, a surface of which has a toothed longitudinal region whichengages with a corresponding pinion 4 housed in a recess of the one orboth guides 8, 8′. The pinion or pinions 4 are driven by a motor 9through a shaft 104. See FIGS. 2 and 11.

[0055] As shown in FIG. 11, the slides 107 and the guides 8, 8′ have across section which forms a mutual undercut for avoiding the slippingout of the slides 107 from the guides when the magnetic structure isrotated together with the table 7 from the horizontal position of thetable to a vertical position.

[0056] Many different designs of the slides and of the guides may bechosen. One simple solution illustrated in FIG. 11 comprises a lateralcontinuous tooth 207 on each slide 107 which engages a lateralcontinuous slot 108 in the corresponding lateral wall.

[0057] Furthermore, nonillustrated releasable locking means of the table7 relative to the magnetic structure 2 are provided. This locking meansmay consist in the combination of the rack and pinion mechanism whichmight be of the nonreversible kind if the motor is deenergised.Alternatively, mechanical locking means, such as releasable lockingteeth engaging the rack, may be provided which means may be drivenalternatively in an active position of engagement and in an inactiveposition of disengagement by means of manual, electric or other kinds ofactuators.

[0058] According to a further feature, the table 7 may be also slidablein a direction transverse to its longitudinal axis, i.e., in a directionperpendicular to the wall 302 of the magnetic structure 2. This may beobtained in a similar way as the method described with reference to thelongitudinal displacement of the table 7.

[0059] According to the illustrated example, the guides 8, 8′ on eachside of the pole 102 are arranged on a transverse slide 10 which engagesa transverse guide 11. The transverse guide and slides may have across-section with mutually engaging undercuts as described withreference to the longitudinal guides and slides and according to FIG.11. The displacement in the transverse directions may be driven by amotor 9′ by means of a combination of racks and pinions as described indetail with reference to the longitudinal guides and slides.

[0060] Also for the transverse displacement of the table 7 releasablelocking means may be provided which may be activated or deactivated asdescribed with reference to the releasable locking means for thelongitudinal displacement of the table 7.

[0061] Thanks to the above disclosed construction, the magneticresonance imaging apparatus according to the present invention allowspositioning of the patient on the table 7 when the magnetic structurewith the table are rotated in an horizontal position of the poles 102,202 and of the table 7.

[0062] In order for the patient to lie on the table 7, the table 7 maybe brought to its maximum longitudinal displacement, as illustrated inFIG. 3. After the patient has taken place correctly on the table, thetable may be displaced relative to the magnetic structure 2 in itslongitudinal direction or if provided also in its transverse direction.FIGS. 4 to 6 illustrates different relative positions of the table 7with respect to the magnetic structure 2.

[0063] The FIGS. 3 to 6 also clearly illustrate that the magneticresonance imaging apparatus according to the present invention allowsnot only to carry out useful images of the vertebral column but due tothe fact that the table 7 might be displaced continuously inlongitudinal and transverse directions, the patient can be brought everytime with a different anatomic region in the examination space formedbetween the two poles 102, 202, thus allowing different kinds ofexaminations.

[0064] In order to reduce the load on the guides and slides of theoverhanging table 7 at its extreme positions (FIGS. 3 and 6), the tablemight be provided at one or both of its ends with a couple of wheeledlegs 15 as is shown in FIG. 1. This allows an extraction of the tablefrom the magnetic structure for almost its entire length, provided theend without the wheeled supporting legs will rest engaged for a terminallength with the magnetic structure.

[0065] Once the patient is on the table 7, the magnetic structure 2 canbe rotated together with the table 7 through an angle of 90°. In thisposition the table is vertical and the patient is in an uprightposition. In order to allow the patient to reach the upright position,at the end of the table associated with the feet a footrest 12 isprovided. This footrest may be fixed or it may be formed by a platewhich is secured in position to the table after having positioned thepatient or the footrest may be formed by a prolongation of the table 7which is hinged to the table 7 in such a way as to be brought andblocked alternatively in the overhanging position and in a positionparallel to the rest of the plate 7.

[0066] As is clear from the FIGS. 7 and 8, the magnetic structure andthe table may be rotated for an angle less than 90°, thus modulating theload on the vertebral column of the patient due to the weight of thepatient itself.

[0067] Once imaging has been carried out, the magnetic structure 2 andthe table 7 can be rotated again in the position where the table 7 ishorizontal. The table can then be displaced to one of its end positions,and the patient can leave the apparatus.

[0068] According to a further improvement illustrated in FIG. 10, aseparate supporting structure 20 may be provided for the table 7. Thisseparate supporting structure is formed by a frame having wheeled legs.The supporting structure 20 is provided on its top with guides 8″ whichare identical in position and cross section to the guides 8,8′ for thelongitudinal slides 107 of the plate 7. Thus by aligning the guides 8″on the separate supporting structure 20 for the plate 7 with the guides8, 8′ of the pole 102, the table 7 may be transferred by longitudinaldisplacement from the said supporting structure 20 to the guides 8, 8′on the pole 102, and vice versa. Thus, the patient might be prepared forexamination on a table outside the magnetic structure while anotherpatient is subjected to examination in the apparatus.

[0069] Because the plate 7 can be inserted in the magnetic structurefrom one side and extracted from the magnetic structure on the oppositeside, and by providing at least two plates 7 with at least twosupporting frames 20 one for each plate, it is possible to control thetraffic of patients to be examined.

[0070] In such a case, the table with a patient who has just finishedthe examination is extracted from the magnetic structure, for example,from the left hand end of the structure 2 of FIG. 10, while the table 7with a following patient is inserted in the magnetic structure from theright hand side of the magnetic structure 2.

[0071] This solution also allows preparation of the patient forexamination on a table outside the magnetic imaging apparatus so that apatient can be prepared for examination while another patient isexamined in the apparatus. Providing a disengagement of the bed or tablefrom the magnetic structure from one side of the magnetic structure andthe engagement of the following bed or table with the magnetic structureon the opposite side of it the apparatus is even more rational regardingthe traffic of patient.

[0072] By providing the supporting structure of the table 7 with guidesoriented perpendicularly to the longitudinal axis of the table 7 itself,the insertion or extraction of the table 7 in and from the magneticstructure 2 can also be carried out in a transverse direction of thetable 7.

[0073] According to a further feature which is shown in FIG. 9, a seatplate 21 may be provided. The seat plate 21 may be secured directly tothe table 7 at different heights or there might be provided a supportingrod 22 which is secured parallel to the plate 7 to the plate itself orto the magnetic structure. The rod 22 carries an overhanging seat plate,the seat plate being secured to the rod by means of a slide engaging therod, releasable locking means being provided for locking the seat plate21 at a desired height.

[0074] Thanks to the above embodiments of the magnetic resonance imagingdevice according to the invention, a method for carrying out theexamination particularly of the vertebral column of a patient can bedefined. An advantage of this method lies in the fact that a simple andnot overdimensioned magnetic structure and patient supporting unit isneeded.

[0075] The magnetic structure of the imaging apparatus is preferably ofthe so called dedicated kind, forming a patient imaging space which isat least shorter than the mean height of adult patients. Such magneticstructures are relatively light and less costly than total body magnetsor similar magnets. Furthermore such dedicated magnetic structures arehandy and can be supported in a displaceable manner without taking intoaccount high expenses for the means which allow the displacement of themagnetic structure.

[0076] In the case of magnetic structures of the dedicated kind, thetable or table plate has a length which is greater that thecorresponding dimension of the poles of the magnetic structure and awidth which is of the order of the corresponding dimension of the poles.

[0077] An embodiment according to the invention allows also a simplerand less expensive patient positioning, due to the fact that the tableand the magnetic structure are supported in a way as to be rotatedtogether, the positioning of the patient, by sliding the tablerelatively to the magnetic structure is carried out in the condition ofrotation of the magnet and of the table in which the table ishorizontal.

[0078] Thus, the means for allowing the sliding displacement of thetable as well as the means for driving the displacement of the table canbe of reduced strength and of reduced power with respect to the solutiondisclosed in the above mentioned prior art documents. This on the otherhand leads to lower costs, weight reduction and a slighter and simplerconstruction.

[0079] Sliding the table with the patient for positioning the patientrelatively to the examining space when the table is horizontal orsubstantially horizontal means that the effects of the weight of thepatient on the sliding movement are reduced to the inertia and to thefriction, while the gravitational effects are suppressed.

[0080] As it might appear clearly, there is no limitation in theposition of the patient relative to the magnetic structure and to theexamining space in it.

[0081] According to a further improvement, the table might also carryout displacements which are in the transverse direction relative to itslongitudinal axis.

[0082] Due to the fact that the bed or table is long with respect to thecorresponding dimensions of the magnetic structure, the patient may laydown on the table or bed without any difficulty since the table or thebed might be displaced in one of the two opposite end positions in whichit extends out from the magnetic structure for a very relevant part.

[0083] It is also to be noted that the bed or table can also be designedin a manner as to be used also in other diagnostic devices or apparati.

[0084] Providing not only a footrest, but also a seat plate which mightbe formed by a section of the bed or table allows examinations of thepatient also in a sitting position.

[0085] In this case there are two options for the patient to enter themagnetic structure. According to a first option the patient enters themagnetic structure with the bed or table in the horizontal position andin lying the patient takes a lying position lying on the bed or tableand against the seat. The magnet and the table can be rotated to asubstantially vertical position of the bed or table and thus moving thepatient to a sitting position. According to a second option, the patiententers the magnetic structure when the bed or table and the magnet arerotated in the vertical position of the bed or table and stands on afootrest or sits down on a seat.

[0086] Relating the way of constructing the means for sliding the tableand for releasably locking it to the magnetic structure and also themeans for rotating table and magnetic structure, the expert in the artis free to choose any kind of known device, such as guides, slides,actuators etc.

[0087] One example of a method according to the present inventioncomprises the following steps:

[0088] Providing a magnetic structure having two opposite poles spacedapart one from the other and oriented substantially perpendicularly to avertical plane and defining a patient imaging space;

[0089] Securing a bed or table for the patient to one of the two polesin a slidable way in the longitudinal direction of the bed or tablerelative to the magnetic structure and between the two poles of themagnetic structure, the bed or table being oriented substantiallyparallel to the poles, the bed or table preferably having a footrest atone end corresponding to the position of the patient's feet;

[0090] Supporting the magnetic structure and the bed or table so thatthe magnetic structure and the bed or table are rotatable togetheraround an axis which is transverse to the longitudinal axis of the bedor table and parallel to the bed or table;

[0091] Rotating the magnetic structure with the table in a patientpositioning position in which the bed or table is substantiallyhorizontal;

[0092] Sliding the bed or table in one of its extreme end positions, inwhich the part of the bed or table being outside the magnetic structureis a maximum;

[0093] Arranging the patient on the bed or table in a lying position;

[0094] Sliding the table or the table along its longitudinal axisrelative to the magnetic structure until the magnetic structure iscorrectly centered with the part of the patient's body to be examined;

[0095] Locking the bed or table relative to a further sliding androtating the magnetic structure together with the bed or table in aposition in which the bed or table is not horizontal or perfectlyvertical;

[0096] Carrying out the imaging procedure;

[0097] Rotating the magnetic structure together with the bed or tableback in a position in which the bed or table is substantiallyhorizontal;

[0098] Sliding the bed or table again in one of the two extremepositions in which the part of the bed or table outside the magneticstructure is a maximum and letting the patient step down from the table.

[0099] Alternative to the phases of sliding the bed or table in one ofthe extreme positions in which the part of the table outside themagnetic structure is a maximum for letting the patient lie down on theplate or step down from the plate, the bed or table may be completelydisengaged from the magnetic structure and at the same time engaged in aslidably way onto an independent and separate wheeled supporting frame.

[0100] Such an alternative embodiment comprises the steps of:

[0101] Providing a magnetic structure having two opposite poles spacedapart one from the other and oriented substantially perpendicularly to avertical plane and defining a patient imaging space;

[0102] Providing a bed or table having at least slides for engagingguides for a longitudinal displacement of the said bed or table;

[0103] Providing a bed or table supporting structure which has wheelsand which is completely independent from the magnetic structure and/orthe imaging apparatus;

[0104] Providing one of the poles of the magnetic structure and the bedor table supporting frame with identical guides with which the slides ofthe bed or table can be engaged;

[0105] Rotating the magnetic structure in a position in which the guidesfor the bed or table are substantially horizontal and aligning the tableor bed supporting frame with its guides aligned with the guides on thepole of the magnetic structure;

[0106] Providing a bed or table supporting structure with a bed or tablearranged on it and letting the patient lie down on the said bed ortable;

[0107] Sliding the bed or table along its longitudinal direction awayfrom the supporting structure and against the pole having the guides andengaging at the same time the free end of the slides of the bed or tablewith the guides on the pole;

[0108] Sliding the bed or table with the patient on it until the plateis completely disengaged from the supporting frame and engaged with thepole of the magnetic structure;

[0109] Sliding further the bed or table along its longitudinal axisrelative to the magnetic structure until the magnetic structure iscorrectly centered with the part of the patient's body to be examined;

[0110] Providing the bed or table with a footrest at one endcorresponding to the position of the patient's feet.

[0111] Supporting the magnetic structure and the bed or table in such away as to be rotatable together around an axis which is transverse tothe longitudinal axis of the bed or table and parallel to the bed ortable;

[0112] Locking the bed or table relative to a further sliding androtating the magnetic structure together with the bed or table with thepatient on it in a position in which the bed or table is not horizontalor perfectly vertical.

[0113] Carrying out the imaging procedure;

[0114] Rotating the magnetic structure together with the bed or tableback in a position in which the bed or table is substantiallyhorizontal;

[0115] Sliding the bed or table back away from the pole of the magneticstructure onto the supporting frame.

[0116] According to a further embodiment, the bed or table istransferred onto the pole of the magnetic structure from the supportingframe and back from the pole on the said supporting frame afterexamination by sliding the bed or table always in the same longitudinaldirection of the bed or table, so that a further step of the methodincludes displacing the supporting frame from the first side of themagnetic structure at which the bed or table has been transferred to thepole to the second opposite side of the pole and aligning the guides ofthe supporting frame with the guides on the pole of the magneticstructure;

[0117] Sliding the bed or table further in the same direction oftransfer for transferring the bed or table with the patient on it fromthe pole again to the supporting frame.

[0118] The above mentioned method may provide a rotation of the magneticstructure together with the patient lying on it from the horizontalposition to a nonhorizontal position which in intermediate with respectto the horizontal position and to the vertical position.

[0119] A further embodiment of imaging may comprise the following steps:

[0120] Providing a magnetic structure having two opposite poles spacedapart one from the other and oriented substantially perpendicularly to avertical plane and defining a patient imaging space;

[0121] Securing a bed or table for the patient to one of the two polesin a slidable way in the longitudinal direction of the bed or tablerelative to the magnetic structure and between the two poles of themagnetic structure, the bed or table being oriented parallel to thepoles.

[0122] Supporting the magnetic structure and the bed or table in such away to be rotatable together around an axis which is transverse to thelongitudinal axis of the bed or table and parallel to the said bed ortable;

[0123] Rotating the magnetic structure together with the bed or table ina position in which the bed or table is not horizontal or perfectlyvertical;

[0124] Providing a seat plate which is secured at an angle to thevertical bed or table;

[0125] Letting the patient sit down on the seat plate;

[0126] Carrying out the imaging procedure;

[0127] Letting the patient step out of the magnetic structure.

[0128] According to a further embodiment, each one of the alternativemethods may further comprise the step of sliding the bed or table or theseat plate transverse to the longitudinal axis of the bed or table.

[0129] Although only preferred embodiments are specifically illustratedand described herein, it will be appreciated that many modifications andvariations of the present invention are possible in light of the aboveteachings and within the purview of the appended claims withoutdeparting from the spirit and intended scope of the invention.

1. A magnetic resonance imaging apparatus, comprising: a magnet having atwo opposite and spaced apart poles and a column or wall transverse tothe poles and connecting the poles; the poles defining two oppositewalls delimiting a patient-imaging space, the two opposite wallsextending along substantially parallel planes which are substantiallyperpendicular to a vertical plane; and a patient positioning table whichis slidably connected to one of the two poles in a position between thetwo poles and which table extends substantially parallel to the twoopposite poles; the table being slidable with respect to the magnet in adirection parallel to a longitudinal axis of the table; a drive fordisplacing the table relative to the magnet; a lock for locking thetable in a selected position relative to the magnet; the magnet beingsupported rotatably along a central horizontal axis of the transversewall or column; a drive provided for rotating the magnet about the axis;the table being connected to the magnet such that the table rotates withthe magnet when the magnet rotates about the axis; the magnet and thetable being rotatable from a position in which the poles and the tableare substantially horizontal to a position in which the table and thepoles are substantially vertical, and vice versa; and the rotation ofthe table and the magnet are locked together by the lock.
 2. Themagnetic resonance imaging apparatus according to claim 1 in which themagnet generates a static magnetic field which permeates thepatient-imaging space and which field is oriented perpendicular to theaxis of the magnetic structure and perpendicular to the two poles and orthe table.
 3. The magnetic resonance imaging apparatus according toclaim 1, wherein the table is displaceable also in a directiontransverse to its longitudinal axis, the extension of the displacementbeing limited to a distance which is equal to a width of the poles alongthe transverse direction or of a width of the table along the transversedirection.
 4. The magnetic resonance imaging apparatus according toclaim 1, wherein the magnet and the table may be rotated from thesubstantially horizontal position to a position having an angle of lessthan 90° with respect to the horizontal position, and vice versa.
 5. Themagnetic resonance imaging apparatus according to claim 1 in which thetable and the magnet are rotatable from a position in which the tableand the poles of the magnet are inclined at an acute angle relative tothe horizontal into a position in which the table and the poles of themagnet are inclined at an acute angle with respect to the vertical. 6.The magnetic resonance imaging apparatus according to claim 1, whereinthe table is mounted on a pole of the magnet which is lower of the twopoles when horizontal by first guides oriented in the longitudinaldirection of the table and perpendicular to the axis of rotation of themagnet, in which first guides the table engages with complementaryslides, and further comprising a motor engaged to a pinion which engagesa rack which is parallel to the first guides.
 7. The magnetic resonanceimaging apparatus according to claim 6, wherein the rack is integralwith at least one of the slides of the table, while the pinion is housedin one of the guides.
 8. The magnetic imaging apparatus according toclaim 6, further comprising second guides at opposite transverse ends ofthe pole to which the table is secured, the said second guides areoriented perpendicular to the first guides and parallel to the axis ofrotation of the magnet, the first guides are engaged in the secondguides by slides which are secured to the first guides while the tableis displaced transverse to its longitudinal axis by a motor activating apinion which engages a rack which is secured to the first guides andwhich is parallel to the second guides.
 9. The magnetic resonanceimaging apparatus according to claim 8, wherein the rack is integralwith at least one of the slides of the first guides, while the pinion ishoused in one of the second guides.
 10. The magnetic resonance imagingapparatus according to claim 1, further comprising a footrest placed atan end of the table.
 11. The magnetic resonance imaging apparatusaccording to claim 11, wherein the footrest is hinged at the end of thetable and is displaceable in an upright angular position where itextends perpendicular to the table and in an inactive position where itis parallel to the table and optionally forms a terminal prolongation ofthe table.
 12. The magnetic resonance imaging apparatus according toclaim 1, further comprising a seat plate fixed to the table.
 13. Themagnetic resonance imaging apparatus according to claim 12, wherein theseat plate is an intermediate section of the table which intermediatesection has two opposite ends oriented transverse to the longitudinalaxis of the table, each of the opposite ends being adjacent to thecorresponding end of one first and one second part of the plate of thebed or of the table and which intermediate section is hinged at one endto the corresponding end of the first or second part of the plate of thebed or of the table in order to let the section being swingable betweena position in which the section extends perpendicular to the plate ofthe bed or of the table and a position in which the said section extendsin the same plane as the first and second parts of the bed or tablewhile means are provided for locking the said section in each one of thetwo positions.
 14. The magnetic resonance imaging apparatus according toclaim 1 in which the table has supporting legs with wheels in a regionat one end thereof.
 15. The magnetic resonance imaging apparatusaccording to claim 1, further comprising a table supporting frame, whichframe has supporting legs for supporting the table in a disengaged orextracted condition from the magnet, the frame having at leastlongitudinal guides which are coincident with the longitudinal guidesfor the slides of the table of the magnet and which are coincident withthe longitudinal slides of the table, the bed or table supporting framebeing freely movable independently from the magnet.
 16. The magneticresonance imaging apparatus according to claim 1, further comprising atable supporting frame, which frame has supporting legs for supportingthe table in a disengaged or extracted condition from the magnet, theframe having at least transverse guides which are coincident with thetransverse guides for the slides of the table of the magnet and whichare coincident with the transverse slides of the table, the tablesupporting frame being freely movable independently from the magnet. 17.The magnetic resonance imaging apparatus according to claim 15, whereinthe table supporting frame has a releasable lock for temporarilysecuring the table supporting frame to the magnet in a position ofalignment of the longitudinal or of the transverse guides of thesupporting frame with the longitudinal or with the transverse guides ofthe magnet.
 18. The magnetic resonance imaging apparatus according toclaim 17, wherein when locked to the magnet, facing ends of the guidesof the table supporting frame and of the guides of the magnet are at adistance one from the other which is smaller than a correspondingdimension of the table.
 19. The magnetic resonance imaging apparatusaccording to claim 1, wherein the table has a length which is greaterthan a corresponding dimension of the poles of the magnet and a widthwhich is of the order of a corresponding dimension of the poles, themagnet being forming a patient imaging space which is at least shorterthan a mean height of adult patients.
 20. A method for magneticresonance imaging with a magnetic structure having two opposite polesspaced apart one from the other and oriented substantially perpendicularto a vertical plane and defining a patient imaging space; and a tablefor a patient secured to one of the two poles in a slidable way in alongitudinal direction of the table relative to the magnetic structureand between the two poles of the magnetic structure, the table beingoriented parallel to the poles, the table having a footrest at one endthereof, the magnetic structure and the table being rotatable togetheraround an axis which is transverse to a longitudinal axis of the tableand parallel to the table, the method comprising: rotating the magneticstructure with the table to a patient positioning position in which thetable is substantially horizontal; sliding the table to an end position,in which a part of the table is outside the magnetic structure;arranging the patient on the table in a lying down position; sliding thetable along its longitudinal axis relative to the magnetic structureuntil the magnetic structure is correctly centered with a part of thepatient's body to be examined; locking the table relative to themagnetic structure together with the table in a position in which thetable is not horizontal or vertical; carrying out an imaging procedure;rotating the magnetic structure together with the table to a position inwhich the table is substantially horizontal; and sliding the table toone of two positions in which a part of the table is outside themagnetic structure and letting the patient step down from the table. 21.The method of claim 20, wherein the imaging is of the vertebral column.22. A method for carrying out magnetic resonance imaging with providinga magnetic structure having two opposite poles spaced apart one from theother and oriented substantially perpendicular to a vertical plane anddefining a patient imaging space; and a table having a footrest at oneend and slides for engaging guides for a longitudinal displacement ofthe table; and a table supporting structure which has wheels and whichis completely independent from the magnetic structure, one of the polesof the magnetic structure and the table supporting frame have identicalguides with which the slides of the table are adapted to engage, themethod comprising: rotating the magnetic structure such that the guidesfor the table are horizontal and aligning the table supporting framewith the guides of the table supporting frame aligned with the guides onthe pole of the magnetic structure; lying the patient down on the table;sliding the table along a longitudinal direction thereof away from thetable supporting frame and against the pole having the guides andengaging at the same time a free end of the slides of the table with theguides on the pole; sliding the table with the patient on the tableuntil the table is completely disengaged from the table supporting frameand engaged with the pole of the magnetic structure; sliding further thetable along its longitudinal axis relative to the magnetic structureuntil the magnetic structure is correctly centered with a part of thepatient's body to be examined; supporting the magnetic structure and thetable in such a way as to be rotatable together around an axis which istransverse to the longitudinal axis of the table and substantiallyparallel to the table; locking the table relative to further sliding androtating the magnetic structure together with the table with the patienton it in a position in which the table is not horizontal; carrying outthe imaging procedure; rotating the magnetic structure together with thetable back to a position in which the table is substantially horizontal;sliding the table away from the pole of the magnetic structure onto thetable supporting frame.
 23. A method according to claim 22, comprisingthe further steps of: displacing the table supporting frame from thefirst side of the magnetic structure at which the table has beentransferred to the pole to a second opposite side of the pole andaligning the guides of the supporting frame with the guides on the poleof the magnetic structure; sliding the table further in the samedirection of transfer for transferring the table with the patient on itfrom the pole again to the table supporting frame.
 24. The methodaccording to claim 22, wherein the magnetic structure and table arerotated to a position in which the table is not vertical.
 25. The methodof claim 22, wherein the imaging is of the vertebral column.
 26. Amethod for carrying out magnetic resonance imaging with a magneticstructure having two opposite poles spaced apart one from the other andoriented substantially perpendicular to a vertical plane and defining apatient imaging space; and a table for a patient to one of the two polesin a slidable way in a longitudinal direction of the table relative tothe magnetic structure and between the two poles of the magneticstructure, the table being oriented substantially parallel to the poles;the magnetic structure and the table being rotatable together around anaxis which is transverse to the longitudinal axis of the table andparallel to the table; the method comprising: rotating the magneticstructure together with the table in a position in which the table isnot horizontal; providing a seat plate secured at an angle to the table;sitting the patient down on the seat plate; carrying out the imagingprocedure; and letting the patient step out of the magnetic structure.27. The method of claim 26, wherein the imaging is of the vertebralcolumn.
 28. The method according to claim 26, wherein the magneticstructure and table are rotated to a position in which the table is notvertical.
 29. The method according to claim 20, comprising the steps ofsliding the table transverse to the longitudinal axis of the table. 30.The method according to claim 22, comprising the steps of sliding thetable transverse to the longitudinal axis of the table.
 31. The methodaccording to claim 26, comprising the steps of sliding the tabletransverse to the longitudinal axis of the table.